package evm

import (
	"context"
	"math/big"
	"time"

	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/pkg/errors"
	"github.com/rs/zerolog/log"
	"github.com/shopspring/decimal"
)

type UniswapRouterContract interface {
	SwapExactTokensForTokens(opts *bind.TransactOpts, amountIn *big.Int, amountOutMin *big.Int, path []common.Address, to common.Address, deadline *big.Int) (*types.Transaction, error)
	GetAmountsOut(opts *bind.CallOpts, amountIn *big.Int, path []common.Address) ([]*big.Int, error)
	AddLiquidity(opts *bind.TransactOpts, tokenA common.Address, tokenB common.Address, amountADesired *big.Int, amountBDesired *big.Int, amountAMin *big.Int, amountBMin *big.Int, to common.Address, deadline *big.Int) (*types.Transaction, error)
}

type UniswapRouter struct {
	name     string
	client   Client
	contract UniswapRouterContract

	deadline time.Duration
}

type UniswapRouterOption func(s *UniswapRouter) *UniswapRouter

func (s *UniswapRouter) WithOperationDeadline(deadline time.Duration) UniswapRouterOption {
	return func(s *UniswapRouter) *UniswapRouter {
		s.deadline = deadline
		return s
	}
}

func NewUniswapRouter(name string, client Client, contract UniswapRouterContract) *UniswapRouter {
	return &UniswapRouter{
		name:     name,
		client:   client,
		contract: contract,
		deadline: 15 * time.Minute,
	}
}

func (s *UniswapRouter) Name() string {
	return s.name
}

func (s *UniswapRouter) SwapTokenToToken(ctx context.Context, path []common.Address, amount decimal.Decimal, slippage decimal.Decimal, opts ...ExecutionOption) (Transaction, error) {
	if len(path) < 2 {
		return nil, errors.Errorf("swap path must contain at least 2 addresses, currently %d", len(path))
	}

	tokenInput, err := s.client.TokenService().TokenByAddress(path[0])
	if err != nil {
		return nil, errors.WithStack(err)
	}

	tokenOutput, err := s.client.TokenService().TokenByAddress(path[len(path)-1])
	if err != nil {
		return nil, errors.WithStack(err)
	}

	log.Debug().Msgf("[SWAP] swaping %s %s to %s with path %v", amount, tokenInput.Symbol(), tokenOutput.Symbol(), path)

	inputBalance, err := tokenInput.Balance()
	if err != nil {
		return nil, errors.Wrap(err, "getting from token balance")
	}

	log.Debug().Msgf("[SWAP] balance of token to swap : %s", inputBalance)
	if inputBalance.LessThan(amount) {
		return nil, errors.Errorf("token balance %s is less than swap amount asked %s", inputBalance, amount)
	}

	expectedout, err := s.contract.GetAmountsOut(&bind.CallOpts{}, tokenInput.ValueToBigInt(amount), path)
	if err != nil {
		return nil, errors.Wrap(err, "getting expected amount in target token")
	}
	decexp := tokenOutput.ValueFromBigInt(expectedout[len(expectedout)-1])
	expectedwithslippage := decexp.Sub(decexp.Mul(slippage).Div(decimal.NewFromInt(100)))
	log.Debug().Msgf("[SWAP] expected amounts : %v", expectedout)
	log.Debug().Msgf("[SWAP] expected ratio : %s", decexp.Div(amount))
	log.Debug().Msgf("[SWAP] expected out with slippage : %s (slippage %s%%)", expectedwithslippage, slippage)
	log.Debug().Msgf("[SWAP] swaping...")
	tx, err := s.client.Execute(ctx, func(ctx context.Context, options *TransactOpts) (*types.Transaction, error) {
		return s.contract.SwapExactTokensForTokens(
			options.TransactOpts,
			tokenInput.ValueToBigInt(amount),
			tokenOutput.ValueToBigInt(expectedwithslippage),
			path,
			s.client.PublicAddress(),
			s.getDeadline())
	}, opts...)
	if err != nil {
		return nil, errors.Wrap(err, "swaping")
	}
	log.Debug().Msgf("[SWAP] swaping done")

	return tx, nil
}

func (s *UniswapRouter) getDeadline() *big.Int {
	return big.NewInt(time.Now().Add(s.deadline).Unix())
}

func (s *UniswapRouter) GetPriceInUSDC(token Token) (decimal.Decimal, error) {
	return s.GetTokenQuoteInUSDC(token, decimal.NewFromInt(1))
}

func (s *UniswapRouter) GetTokenQuoteInUSDC(token Token, amount decimal.Decimal) (decimal.Decimal, error) {
	usdc, err := s.client.TokenService().TokenBySymbol("USDC")
	if err != nil {
		return decimal.Zero, errors.Wrap(err, "getting usdc token")
	}
	return s.GetAmountRate(token, usdc, amount)
}

func (s *UniswapRouter) GetRate(token0 Token, token1 Token) (decimal.Decimal, error) {
	return s.GetAmountRate(token0, token1, decimal.NewFromInt(1))
}

func (s *UniswapRouter) GetAmountRate(token0 Token, token1 Token, amount decimal.Decimal) (decimal.Decimal, error) {
	if amount.LessThanOrEqual(decimal.Zero) {
		return decimal.Zero, nil
	}
	expectedout, err := s.contract.GetAmountsOut(&bind.CallOpts{}, token0.ValueToBigInt(amount), []common.Address{token0.Address(), token1.Address()})
	if err != nil {
		return decimal.Zero, errors.Wrap(err, "getting expected amount in quote token")
	}
	return token1.ValueFromBigInt(expectedout[len(expectedout)-1]), nil
}

func (s *UniswapRouter) AddLiquidity(ctx context.Context, token1 Token, token2 Token, amounttoken1 decimal.Decimal, amounttoken2 decimal.Decimal, opts ...ExecutionOption) (Transaction, error) {
	return s.client.Execute(ctx, func(ctx context.Context, options *TransactOpts) (*types.Transaction, error) {
		return s.contract.AddLiquidity(
			options.TransactOpts,
			token1.Address(),
			token2.Address(),
			token1.ValueToBigInt(amounttoken1),
			token2.ValueToBigInt(amounttoken2),
			token1.ValueToBigInt(amounttoken1.Sub(amounttoken1.Mul(decimal.NewFromFloat(0.01)))),
			token2.ValueToBigInt(amounttoken2.Sub(amounttoken2.Mul(decimal.NewFromFloat(0.01)))),
			s.client.PublicAddress(),
			s.getDeadline())
	}, opts...)
}